Known silicone fine particles include fine particles having rubber elasticity (silicone elastomer fine particles) and fine particles of a polyorganosilsesquioxane resin, and these particles have been incorporated in cosmetic products for the purpose of giving dryness, smoothness, and other textures as well as spreadability with the product. More specifically, the inventors of the present invention proposed polyorganosilsesquioxane-coated silicone fine particles in JP-A H07-196815, and these particles are used in many cosmetic products due to the soft texture, reduced agglomeration, and excellent dispersion.
In the method proposed in JP-A H07-196815, an alkaline substance or an alkaline aqueous solution and an organotrialkoxysilane are added to an aqueous dispersion of spherical fine silicone elastomer particles to thereby promote hydrolytic condensation. The fine particles prepared by this method are spherical fine silicone elastomer particles coated with a polyorganosilsesquioxane, and the silicone elastomer particles have polyorganosilsesquioxane particles attached to their surface, and the polyorganosilsesquioxane particles have an approximate size of 100 nm. Due to the light scattering effects of the polyorganosilsesquioxane, natural finish with no unnatural gloss is realized when added in foundations and other makeup cosmetic products. In these days, such non-artificial natural finish (bare skin texture) is highly valued, and there is a demand for a higher light scattering property.
JP 3452562 proposes a method for producing spherical polyorganosilsesquioxane fine particles in the shape of pointed sugar candy balls having projections on the surface of the particles. JP-A 2004-359592 proposes a cosmetic product having such spherical polyorganosilsesquioxane fine particles incorporated therein, and the projections on the surface are said to dramatically improve the optical properties and camouflage pores and wrinkles of the skin. Particles having the projections with the diameter of 400 nm, 600 nm, and 800 nm are described, and provision of the projections with such diameter not shorter than the wavelength (approximately 400 to 800 nm in the case of visible light) are estimated to contribute for the high light scattering property. The polyorganosilsesquioxane fine particle, however comprises a resinous hard material, and it can not be provided with a soft texture.